BI Intelligence's data shows that WeChat, LINE, WhatsApp, and Snapchat are all growing their user numbers in 2014 at a quarterly rate of 15% or higher.

Like social networks before them, these apps are becoming the hubs for everything global smartphone audiences do on mobile. Messaging apps help people connect with one another, share photos, video chat, and increasingly engage in activities that earn significant revenue for the apps, including playing games, buying digital goods, and even shopping offline.

User sessions for messaging and social apps increased 203% in 2013, according to Flurry. That's about twice as fast as the increase in sessions for all types of apps, which was 115% for the year.